1. Technical Field
The present invention relates to an IC card suitable for use in various devices such as various information devices, video devices, and communication devices, including small portable devices.
2. Description of the Related Art
In the present specification, a memory card such as an IC memory card that incorporates a semiconductor memory and is used as an information medium for storing information of various types such as data, audio signals, and video signals, a card-type device or PC card having functions other than the information storage function, such as a communication function or an interface function, and a card-type device or PC card that has both the information storage function and the other function are generally termed as an IC card (Integrated Circuit Card). A variety of small and lightweight IC cards, including those of a postage stamp size, have recently been developed and put to practical use. FIG. 20 shows an external appearance of an IC card which is an example of the conventional IC card.
The IC memory card 1 shown in FIG. 20 comprises a memory card body 2 incorporating a semiconductor memory inside thereof. External connection terminals 5 (5a-5i) for electric connection of the semiconductor memory to external devices are provided in a vicinity of an edge on one side of a lower surface of the memory card body 2. Examples of external devices include a variety of information devices, video devices, and communication devices. Further, the IC memory card 1 comprises a write-protect switch 9 for preventing erroneous deletion at a side edge of the memory card body 2. Detection of the status of the write-protect switch 9, which is a physical switch, is performed on the external device side. More specifically, a detection mechanism for detecting the position or status of the write-protect switch 9 is provided at the external device using the IC memory card 1 or at a connector for connecting the memory card 1 to the external device. The write-protect switch 9 of this type is described in Japanese Patent Application Laid-open Publication No. 2001-52135.
It was also suggested to incorporate a write-protect switch inside the memory card body, rather than on the side edge thereof. However, because a memory card is small in size and thin, the switch intended to be incorporated in the memory card body has to be manufactured with high accuracy to small thickness. Further, when a height of the incorporated switch is large, a space or height for accommodating the switch has to be ensured by providing a through hole in a substrate accommodated inside the memory card body and mounting the switch in the through hole.
The increased level of semiconductor component integration made it possible to realize a high-capacity IC memory card or a multifunctional card-type device or PC card. However, some of the presently employed devices are not adapted to such high-capacity IC memory cards or multifunctional card-type devices, and ensuring the compatibility sometimes becomes a problem. Thus, the progress of the IC card to a higher capacity and a large number of functions is being advanced, whereas it is necessary to ensure compatibility with the presently available devices of limited capacity or functions.